‘Forbidden’ rice may rival blueberries as antioxidant source

The anthocyanin content of black rice may rival that of the blueberries and blackberries, and be available for a fraction of the cost, suggests new data from Louisiana.

Black rice, or ‘Forbidden Rice’ as it was known in ancient China, is a rich source of anthocyanin antioxidants and could offer food manufacturers an alternative to berries for a range of products, including breakfast cereals, beverages, cakes, cookies, and other foods. The results were presented at the 240th National Meeting of the American Chemical Society (ACS)

“Just a spoonful of black rice bran contains more health promoting anthocyanin antioxidants than are found in a spoonful of blueberries, but with less sugar and more fiber and vitamin E antioxidants,” said Zhimin Xu, Associate Professor at the Department of Food Science at Louisiana State University Agricultural Center in Baton Rouge.

“If berries are used to boost health, why not black rice and black rice bran? Especially, black rice bran would be a unique and economical material to increase consumption of health promoting antioxidants,” added Dr Xu.

Market potential

Data from Leatherhead Food International (LFI) shows that the world functional antioxidants market is increasing year on year by around 3 per cent, and was valued at US$ 400 million in 2004, and US$ 438 million in 2007. Europe, the US, and Japan account for 90 per cent of this market.

With flavonoids and polyphenols reported to be 45 per cent of this functional antioxidant market, equivalent to almost US$ 200 million,

Black rice

Dr Xu and colleagues analyzed samples of black rice bran from rice grown in the southern United States, and found that, in addition to high contents of gamma-tocotrienol (vitamin E), and gamma-oryzanol antioxidants, black rice bran possess higher level of anthocyanins antioxidants, which are water-soluble antioxidants.

The Louisiana-based scientists also told attendees at the ACS meeting that pigments in black rice bran extracts may also produce a variety of different colors, ranging from pink to black, and offer ‘natural’ options for foods and beverages.

Dr Xu noted that farmers in Louisiana have already expressed an interest in growing black rice and that he would like to see people in the country embrace its use.

Structure is key

Polyphenols, and flavonoids in particular, are not all created equal. For example, scientists from The Ohio State University reported that the structure of anthocyanins, the antioxidant pigments from a range of fruit and vegetables, is key to the cancer fighting abilities.

According to findings published in the Journal of Agricultural and Food Chemistry (doi: 10.1021/jf8005917), certain types of anthocyanins have greater activity against colon cancer than others.

“The chemical structures of anthocyanins do have a significant impact on their biological activity, and data suggest that non-acylated monoglycosylated anthocyanins are more potent inhibitors of colon cancer cell growth proliferation,” wrote lead author Pu Jing.

The researchers cautioned that more research is necessary to explore the role of anthocyanin structure and the chemo-protective effects.

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